Many types of structures exist for oil and gas exploration, however few exist that can perform drilling and production operations and be moveable. Still fewer structures can perform drilling, production, and workover operations in deep waters, far from shore.
A need has existed for an improved, versatile vessel that can be used for demanding drilling operations in deep waters, yet be a floating vessel that can be towed from site to site for work.
Additionally, a need has existed for a vessel that is transparent to the motion of the waves about the lower portions of the rig, while having a center of gravity below the center of buoyancy to reduce the effects of heave and roll motion during use.
A need has existed for a rig that can additionally reduce the effects of pitch, yaw, and sway on risers connected to the rig.
The present invention contemplates reducing or eliminating many of the drawbacks associated with other conventional deep water rigs, and providing a mobile, stable rig, having superior motion characteristics and reduced response to wind and wave forces.